RE: Deadlock

From: <Jared.Still_at_radisys.com>
Date: Thu, 19 Dec 2002 17:53:44 -0800
Message-ID: <F001.0051F38C.20021219175344@fatcity.com>

See Note 164661.1 on MetaLink for an excellent explanation of deadlocks.

Jared

"Fink, Dan" <Dan.Fink_at_mdx.com>
Sent by: root_at_fatcity.com
 12/19/2002 02:04 PM
 Please respond to ORACLE-L  

        To:     Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
        cc: 
        Subject:        RE: Deadlock


Seema,
                 Changing INITRANS may help IF you see waits for data 

block headers.
INITRANS/MAXTRANS deal with the number of transactions that can lock a block
at a given time.

                 Deadlocks are caused when TransactionA has locked RowA 

and TxB has
locked RowB. Then TxA needs to lock RowB (but can't because TxB has locked it) and TxB needs to lock RowA (but can't because TxA has locked it). The locks won't be released until the transaction completes, but they cannot complete successfully since they cannot acquire the needed lock. So you have
a round robin affair. The transaction discovering the deadlock will be rolled back.

                 Check the application code. Therein lies the problem.

Dan Fink

-----Original Message-----

Sent: Thursday, December 19, 2002 12:55 PM To: Multiple recipients of list ORACLE-L

Hi
I have been noticing some times following error with one table during update.

DEADLOCK DETECTED
Current SQL statement for this session:
"The following deadlock is not an ORACLE error. It is a deadlock due to user error in the design of an application or from issuing incorrect ad-hoc SQL. The following information may aid in determining the deadlock:"

Is chaning of INITTRANS would help ?
Thx
-Seema

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Author: Seema Singh
  INET: oracledbam_at_hotmail.com

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Author: Fink, Dan
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  INET: Jared.Still_at_radisys.com

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